The Present Application relates, generally, to both a cooling device and an electronic device for unifying the function of efficiently refrigerating heat received from a heating element of an electronic device.
Electronic parts, used in electronic devices, for example, are heating elements that generate heat according to the current flows within. When the heating element is operable, and the temperature thereof hits a constant temperature, the efficient operation of the device diminishes, causing the performance of the electronic device to deteriorate.
In order to cool a heating element, the cooling device utilizing a heat pipe possessing the cooling effect according to the vaporization and condensation of a entered refrigerant is proposed. When the refrigerant evaporates, the heat pipe takes heat from the heating element. The evaporated refrigerant is refrigerated and condensed by radiating heat. The condensed refrigerant circulates again. By repetition of the vaporization and condensation, the heat pipe refrigerates the heating element.
The heating element mounted on an electronic device or industrial equipment is provided in the electronic device or the industrial equipment. The heat from the heating element is necessary to be radiated to the part which is isolated from the heating element.
The cooling device possesses: a thermal diffusion function of taking and then diffusing the heat of the heating element; a heat transporting function of transporting the diffused heat to the part operable to radiate the heat; and a heat radiating function of radiating the transported heat. The cooling device comprises the structure for realizing the three functions, and refrigerates the heating element included in the electronic device or the industrial equipment.
Some technologies related to such a cooling device are proposed. For example, Japanese Patent No. 3233808 discloses a cooling system operable to move heat from a heating element to a heat radiating member, and to refrigerate the heat. In the '808 Patent, it is assumed that the heating element possessing a large calorific value itself, such as a semiconductor integrated circuit, is a cooling target. The heat from the heating element is conducted to a heat receiving unit, a thermal conductivity element, and a heat radiating unit. Then, the heating element is refrigerated. In other words, when the heat is taken from the heating element, the taken heat is transported by the thermal conductivity element, and the transported heat is conducted by the heat radiating unit. Each of the heat receiving function, the heat transporting function, and the heat radiating function is formed by a different member. Each member is connected each other.
Further, Japanese Patent Application No. 2004-037001 discloses a technology operable to move a refrigerant evaporated by heat from a heating element to another member through a pipe, and to refrigerate the refrigerant by a secondary cooling member such as a heat sink, in the member of another object. Dissimilar to the heat pipe according to the '808 Patent, the function of diffusing the received heat although possessing a plate-like shape, and the function of transporting the diffused heat are unified in a main body possessing the plate-like shape.
Additionally, Japanese Patent Application No. 2003-075083 discloses a technology that a vertically arranged heat pipe transports and radiates heat from a heat source. Finally, Japanese Patent Application No. 6-216555 discloses a technology, in which a cooling device is arranged on the end face of a heat pipe formed in two layers, and thermal diffusion and heat radiating are included.
Since the thermal diffusion function, the heat transporting function, and the heat radiating function shown in the '808 Patent are formed by different members, there is a problem that the heat pipe is enlarged and complicated. The electronic component, which is a target for cooling recently, is a semiconductor integrated circuit considered as large, such as a CPU (Central Processing Unit) or a dedicated IC, or is often a very compact electronic component, such as a high luminance LED (Light-Emitting Device). In such a case, the heat pipe possessing a large-sized and complicated shape is disadvantageous in respect of mounting.
Furthermore, in the hear pipe possessing the thermal diffusion function, the heat transporting function, and the heat radiating function, which are formed by different members and connected mutually, in each of heat movement from the thermal diffusion function to the heat transporting function, and heat transport from the thermal transporting function to the heat radiating function, since the thermal resistance becomes high, the efficiency of the heat movement becomes worse.
As for the heat pipe shown in the '001 Application, the thermal diffusion and the heat transport are unified. However, even if unified, the heat needs to move between different members. Thus, the efficiency from the heat diffusion function to the heat transporting function is still bad. Moreover, since in the heat pipe according to the '001 Application, the fin as a heat radiating member is provided with the predetermined position of the heat pipe, it is necessary to intensively transport the heat to the predetermined position. However, since the thermal diffusion function and the heat transporting function are unified, depending on a shape, a size, an arrangement position, and a calorific value of the heating element, it is hard for the heat of the heating element to efficiently move to the position of the fin. For this reason, as for the heat pipe according to the '001 Application, the thermal diffusion, the heat transport, and the heat radiating are not suitably combined.
The heat pipes shown in the '083 and '555 Applications are plate-like shaped heat pipes, which the heat receiving function and the thermal diffusion function are unified. Since such a plate-like shaped heat pipe is compact and thin, it can be easily mounted on various kinds of apparatus. There are, however, the following problems in the plate-like shaped heat pipes shown in these Applications since the thermal diffusion function, the heat transporting function, and the heat radiating function are realized with a single member: (1) The ability of heat radiating tends to be low (when the capability of heat radiating is low, the condensation of the evaporated refrigerant becomes slower, thus, the cooling ability of the heat pipe becomes low); (2) Since the thermal diffusion and the heat transport are unified, the diffusion direction and the transporting direction of the heat must be the same, and can not be different; and (3) Since the diffusion direction and the transporting direction can not be distinguished with each other, it is difficult to lead the heat to the heat radiating member.
As mentioned above, when the functions possessed by the heat pipe are decomposed, the heat pipe needs to comprise the diffusing function of the heat received from the heating element, the heat transporting function, and the heat radiating function. When all of these functions are formed and combined by the different forms, there are problems that the heat pipe becomes large, and the heat transfer efficiency is deteriorated. On the other hand, if these functions are formed with the single member, the deterioration of cooling ability based on the problems (1) to (3) mentioned above, is caused.
In addition, according to the conventional cooling device, a position of a heating element and a position of heat radiation can not be arranged differently from each other in an electronic device or an industrial apparatus.
Accordingly, a cooling device are requested to possess the following points: (A) The heat can be moved to the heat radiating position located at the position which is different from the position of the heating element with high efficiency; (B) While the thermal diffusion and the heat transport can be distinguished functionally, the decrease of the efficiency for the heat movement can be suppressed to a minimum; (C) Movement of the heat from the heating element to the heat radiating position can be realized also in a complicated shape; (D) Since the cooling device is compact and thin in order not to spoil the miniaturization of an electronic device or an industrial apparatus, it is possible to be mounted to the electronic device or the industrial apparatus; and (E) The cooling ability can be kept high.